Most appliances, sensors, machinery, electronic and industrial devices which implement more than a trivial on/off communication with another device and which enable a change of state or report data, implement a protocol. There are many standard protocols which enable interoperability between devices and compatible remote controllers, however, many manufacturers implement proprietary protocols for which no documentation exists or for which no remote controllers are manufactured any longer. At times, a remote controller is solely a configuration system or testing device. Many devices in the field are no longer supported either because the product is obsolete or the manufacturer is no longer in existence. Typical reverse engineering of the class of product described above takes months and can be haphazard. It is difficult and complex for the average user to rebuild the protocols of these systems, and doing so typically involves the use of human experts with fairly developed experience, specialized knowledge, and lots of tinkering.
Most users do not seek to emulate their remote controls because they can simply replace them or interface with their device via the built-in controller. In addition, the focus of reverse engineering today is concerned with security research or illicit access to higher level Information Technology systems. Such systems running on sophisticated computer servers utilize highly sophisticated software. These systems implement large language vocabularies with inherently complex virtual states. These virtual states are not apparent to the operator since they do not produce a physical process in the sensible realm, therefore, these are the systems that are targeted by reverse engineering tools.